Based on the results from the first 2 years of the grant, we have determined the appropriate alcohol containing liquid diets for producing offspring that serve as a useful rat model of human FAS. We have also confirmed that prenatal ethanol produces dramatic effects on brain beta-endorphin as determined at the biochemical, anatomical and behavioral levels. In the current proposal we will test the hypothesis that ethanol's action results in inappropriate production of pro-opiomelanocortin (POMC) gene products. The proposal describes studies to measure beta-endorphin and POMC mRNA during the prenatal course of ethanol treatment. These will be assessed both at the biochemical and histological level. One objective is to determine the exact time during gestation that ethanol perturbs POMC gene activity. Another series of studies uses the POMC probe to study that genes' activation in the hypothalamus in adult FAs offspring after certain stress sitatuations. We will characterize the composition (with HPLC separation) and levels (with specific RIA) of POMC peptides in hypothalami, as well as POMC mRNA. The comparison of the activation of the gene and its products after stress between control pair-fed and alcohol exposed rats may provide some insight to the abnormal responses to stress that are seen in FAS offspring. The post-synaptic side of the endogenous opioid systems will be explored with our continuing study of opiate receptors, especially the kappa subtypes, for which we devised a new method of assessment. Some of the most exciting data we have seen arose from studies of neonatal behaviors in 10 day-old offspring. These results, showing greatly abnormal responses that utilize the endogenous opioid systems, have implications for alterations, at the cellular level, in receptor populations, and at the systems level, for the formation of learned affectational responses. Increased beta-endorphin levels have now been seen in both FAs rats and monkeys, and may be a general feature of FAS that could have clinical implications. We plan to administer small timed-release implants of the opiate antagonist, naltrexone, to rat pups born to alcohol and control mothers. Our hypothesis is that the excess beta-endorphin produces changes in opiate receptors that cause or contribute to the abnormal development of the CNS in these offspring.